(CNN)The UK Home Office destroyed landing card slips that documented arrival dates for the so-called Windrush generation, it confirmed Wednesday, an admission that has added to pressure on the government over its treatment of some Caribbean migrants.
UK Home Office destroyed Windrush landing card slips
The landing card slips were "securely disposed" of in 2010, the Home Office said. UK Prime Minister Theresa May was Home Secretary at the time in the Conservative government of former premier David Cameron.
The confirmation came a day after May publicly apologized for any "anxiety" caused to the Windrush generation -- the first large group of Caribbean migrants to arrive in the UK after World War II.
Her words followed widespread condemnation of the government's treatment of the Windrush generation, some of whom are facing deportation after decades living in Britain because they don't have the right paperwork.
In a statement Wednesday, the Home Office said that "in 2010, the decision was taken by the UK Border Agency to securely dispose of some documents known as registration slips." This decision was made in line with the Data Protection Act 1998, under which the Home Office has a "legal obligation to ensure that the personal data it holds is not kept for longer than is necessary."
However, speaking during Prime Minister's Questions in the House of Commons, May stated that the decision to destroy the documents had been made in 2009, when a Labour government was in power.
The Home Office also argued that the landing card slips did not provide proof of residence.
"Registration slips provided details of an individual's date of entry, they did not provide any reliable evidence relating to ongoing residence in the UK or their immigration status," a Home Office spokesperson said.
"So it would be misleading and inaccurate to suggest that registration slips would therefore have a bearing on immigration cases whereby Commonwealth citizens are proving residency in the UK."
The Guardian reported Tuesday that the documents were destroyed when a Home Office branch was closed down in 2010.
Addressing lawmakers Wednesday, May sought to draw a line under the controversy over her government's treatment of migrants from the Windrush generation.
"People in the Windrush generation who came here from Commonwealth countries have built a life here, they've made an enormous contribution. These people are British. They are part of us," she said.
"I want to be absolutely clear: We have no intention of asking anyone to leave who has the right to remain here. For those who have mistakenly received letters challenging them -- I want to apologize to them and I want to say sorry to anyone who has been caused confusion or anxiety felt as a result of this."
Opposition Labour leader Jeremy Corbyn slammed what he called a "shameful episode" and said responsibility for the situation "lies firmly at the Prime Minister's door" because of her actions while Home Secretary.
Earlier, Shadow Home Secretary Dianne Abbott, a Labour member of Parliament, told BBC Radio 4 that current Home Secretary Amber Rudd should "consider her position" over her department's handling of the issue.
"There are so many things that have gone wrong. This is not a new situation, it's been going on for some years," said Abbott, as she called for the Home Office to make public the information it holds on the number of people who have been detained or deported.
"This has caused so much misery and has ruined so many people's lives," she said.
May apologized at a meeting with Caribbean leaders and insisted the Windrush generation was still welcome in the country.
May said her government was "genuinely sorry for any anxiety that has been caused" and that Home Office personnel were "dealing with this as well and efficiently and swiftly as they can and giving people every support that we can give them."
May acknowledged that the crisis had arisen because of tough new rules imposed during her time as Home Secretary in an effort to crack down on illegal immigration.
The measures, introduced in 2012, require employers, landlords and health service providers to demand evidence of legal immigration status. At the time, May said they were designed to create a "hostile environment" for people living in the UK illegally.
But some of the Windrush children, who were invited along with their parents to Britain in the late 1940s to help rebuild the country after the devastation of World War Two, don't have the required documentation and are now struggling to prove their right to stay.
As a consequence, some lost their jobs, others were evicted from their homes and a few were reported to have been threatened with deportation.
On Tuesday, the Home Office told CNN it was looking into 49 cases relating to the Windrush generation after a new hotline was established to help those affected obtain the correct paperwork.
Until an immigration law that came into force in 1973, Commonwealth citizens and their children had the automatic right to live and work in the UK. Many did so, without any need for additional documentation.